B1302 Accessory Delay Relay Coil Circuit Failure

Definition

Common causes

• Faulty accessory delay relay
• Damaged wiring or connectors
• Short circuit in the relay circuit
• Open circuit in the relay circuit
• Malfunctioning body control module (BCM)
• Corroded terminals or connections
• Faulty ignition switch
• Battery issues or low voltage

Common misdiagnoses

• Faulty battery
• Bad ground connections
• Malfunctioning ignition switch
• Defective body control module (BCM)
• Wiring issues or shorts in the circuit
• Faulty accessory delay relay
• Issues with other relays or fuses in the system

Troubleshooting steps

1. 1. Check the Vehicle's Battery

   Ensure the battery is fully charged and in good condition. A weak or failing battery can cause various electrical issues

2. 2. Inspect Fuses

   Check the fuses related to the accessory delay relay and other related circuits. Replace any blown fuses

3. 3. Examine the Relay

   Locate the accessory delay relay in the fuse box or relay panel. Inspect it for any signs of damage or corrosion. If necessary, swap it with a similar relay to see if the problem persists

4. 4. Inspect Wiring and Connectors

   Check the wiring and connectors associated with the accessory delay relay circuit for any signs of damage, corrosion, or loose connections. Repair or replace any damaged components

5. 5. Test the Relay Circuit

   Use a multimeter to test the relay coil circuit for continuity and proper voltage. Ensure that the relay is receiving the correct voltage when the ignition is in the appropriate position

6. 6. Check for Short Circuits

   Inspect the circuit for any short circuits that may be causing the relay to fail. This can include checking for damaged insulation or pinched wires

7. 7. Scan for Additional Codes

   Use an OBD-II scanner to check for any additional trouble codes that may provide more context or indicate related issues

8. 8. Inspect the Body Control Module (BCM)

   If all other components check out, the issue may lie within the Body Control Module (BCM). Inspect the BCM for any faults or failures, as it controls many accessory functions

9. 9. Consult Wiring Diagrams

   Refer to the vehicle’s service manual for wiring diagrams to understand the circuit layout and identify any potential issues

10. 10. Clear the Code and Test Drive

    After performing repairs, clear the trouble code using an OBD-II scanner and take the vehicle for a test drive to see if the code returns.1

11. 11. Seek Professional Help

    If the issue persists after performing these steps, it may be necessary to consult a professional mechanic or technician for further diagnosis. By following these troubleshooting steps, you should be able to identify and resolve the issue related to the B1302 code